Brown argus ab

[Rivoldini]

Hello,
I photographed this argus in County Durham this morning as it stood out from the others. I have provisionally identified it as aricia agestis ab. snelleni+ semi-allous. I would welcome being corrected or confirmed on this

Thank you, all keep safe

Riv.

[David M]

Great specimen, Riv. I'll leave it to others to pronounce on the exact ab. but it's certainly a highly unusual BA.

[Allan.W.]

That is very unusual Rivoldini ,never seen anything quite like that !...………… Great find !
Regards Allan.W.

[Pete Eeles]

If this was taken in County Durham, then it's a Northern Brown Argus, I believe

Cheers,

- Pete

[Rivoldini]

Not where this one was, both arguses are found there and Brown Arguses are found now at another nearby site.

[petesmith]

I think from the location that ab.dominico-cummingsii is the most likely ID

[Rivoldini]

2019: This year we had 47 records sent in from sixteen different sites. The total of 286 butterflies seen flying makes it the best year ever for Brown Argus in the region. It would also seem from the numbers recorded during the spring that the butterfly is definitely breeding on some sites here. Perhaps the good summer the year before (2018) meant successful breeding was possible and we are seeing the results of that. Nevertheless we are right on the northern limit of its range here, and the situation could easily be reversed. On the other hand we could be seeing the effects of climate change on the distribution of the Brown Argus. The first record of the year came from Martin Partridge who reported seeing two at the Johnson Matthey Biodiversity site near Billingham on 13thMay. This is a site where it is certainly breeding. Martin reported several double figure counts duringthe spring generation peaking at 23 seen on 22ndMay. The only other spring count in double figures was from Dave Wainwright with 14 at BP CATS at Seal Sands on 4th June. Unlike previous years when only one or two sites reported Brown Argus flying in spring, this year records were received from eight different sites. In August the second generation started to emerge, although the numbers seen were not as high as for the spring generation. All the double figure counts were from the Johnson Matthey Biodiversity site, with the maximum being 15 on 8th August. Records from several different recorders were also received from the Kelloe Bank / Raisby Way sites, again a likely breeding location. Brown Argus was also seen on sites around Hartlepool and Seaton Carew dunes. Most records were from the South East corner of County Durham and Tees-side but some were from further afield, such as the Sunderland area, Blackhall Rocks, Dalton Park and Wingate Quarry. The flight season had ended by the last week of August but four records were received for September. However, the last sighting was not until 17th October when Bob Mawson saw one at Kelloe Bank, Raisby Way, a very late date indeed. This year was an exceptional year for the Brown Argus, the 286 seen was by far the highest number ever reported. Let's hope this marks the start of it establishing itself in County Durham more widely and more permanently. From BC NE Area annual report 2019

[Pete Eeles]

Not where this one was, both arguses are found there and Brown Arguses are found now at another nearby site.

Ooh - interesting! So how do you tell them apart at such sites? I've relied on location for far too long

Cheers,

- Pete

[Rivoldini]

OK Peter, I first came across this enigma in 2018 when I saw and photographed a freshly emerged argus in the middle of August at Bishop Middleham Quarry. On the basis of the old adage that arguses seen in late July onwards are Brown Arguses I sent the photo to the local recorder and he said "What you have there is a female Brown Argus". "They were first recorded there the previous September". I live 30 minutes away from BMQ and have since kept an eye on them. Agestis is also found in two other nearby quarries where rockrose does not go leaving it in no doubt apparently that these can not be artaxerxes-salmacis.

This year arguses have been out at BMQ for about ten days and this mornings count was ten including the previously featured aberrant one, another aberration and one with the Scottish white spot on the fore wings. I have no idea at all how one can differentiate the spring arguses although there is no problem with the late sumer ones. At the moment I assume that agestis emerge earlier than artaxerxes and therefore when fresh ones appear a few weeks later they could in fact be artaxerxes but that is purely non scientific. I welcome very much any guidance on the matter so it can be confirmed and clarified for the future.

The attached photos were all taken this morning.

[Pete Eeles]

Thanks! There's definitely significant variation between individuals - especially the underside spotting, so I can see why someone might suggest Brown Argus and any second brood individual (late in the year) is almost certainly going to be Brown Argus. However, the only reliable means of separating the two species is by DNA testing, as far as I'm aware, and at this time of year, I'd doubt that anyone can tell the two species apart, given the normal bounds of variation - although those at either extreme are probably good indicators.

Life was much simpler when we could rely on location

Cheers,

- Pete

[Rivoldini]

Hi Peter, thank you for your response. I totally agree with you about the separations of the spring ones, virtually impossible. Today the numbers had increased to 30 which I would assume are now all NBAs. I'll keep an eye out for the second brood and let you know the situation then, Take care, Riv.
PS your book is the tops, but you already know that.

[Pete Eeles]

Thanks Riv - on all counts!

Cheers,

- Pete